PATTERN MAKING 



American 
School of Correspondence 



Copyrighted 1898 

BY 

American School of Correspondence 



BOSTON, MASS., 
U. S. A. 



K ^AVi\xj, s : '<K 



vs 



■ 



*& 



Ifjy-woy-rdJ- 



PATTERN MAKING 



INSTRUCTION PAPER 



American 
School of Correspondence 



Uowt"^i 



ff^^ 



Copyrighted 1898 

BY 

American School of Correspondence 



BOSTON, MASS., 
U S. A. 

8EP.301 

IPIES RtufiVED. 






8278 



«i 



PATTERN MAKING. 



Pattern making dates back to the time when the first article 
was made from molten metal for the use of man. The pattern 
must precede the making of its metal counterpart, and is, there- 
fore, the first subject to be treated in the working of metal. 

Qualifications of the pattern maker. The pattern maker is 
essentially a worker in wood, though where many pieces are to be 
cast from a single pattern it is frequently made of metal. He 
should, however, possess an intimate knowledge of the properties 
of metals. First of all, he must understand the shrinkage of 
metals, that is to say, how much smaller the cold casting will be 
than the molten mass as it flows into the mould ; he should know 
what the strength of the metal is ; he should be familiar with the 
relative rapidity of cooling so that internal stresses in the body of 
the completed casting may be avoided as much as possible; he 
must also know enough about the practical work of the moulder to 
decide upon the peculiarities of construction of the pattern for any 
given piece ; and he must be enough of a draughtsman to lay out 
the drawings of the piece to be made without the assistance of the 
designer. It is very true, however, that there are many pattern 
makers who do not possess all of these qualifications. 

The last mentioned qualification is one of the most important. 
The drawings furnished the pattern maker are usually on a small 
scale, and in order to work to the best advantage, he is expected 
to reproduce a part or all of them in full size upon a chalked 
board. This does not require the same nicety and precision of 
workmanship that is called for in the drawing room; but it is 
essential that the pattern maker have the same complete knowl- 
edge of the principles involved. To the extent, then, of being 
able to make a full size drawing of the article to be made, upon 
a chalked board, the pattern maker must be a draughtsman. 

In large establishments where all work comes to the pattern 
shop as carefully executed drawings, the pattern maker is the 
means of putting the ideas of others into a tangible form. In 
smaller places, where no draughtsman is employed, the pattern 



^-/>/ 



PATTERN MAKING 



maker will be called upon to work out the designs from which he 
is to make his patterns and he thus becomes the real designer. 

Finally, the pattern makeris seldom required to make two 
patterns that are identically the same. His work is, therefore, 
varied and he must be prepared to apply to the solution of new 
problems, such principles as he may have learned. 

flaterials for Patterns. As patterns are subjected to more 
or less rough usage, and are alternately wet and dry, it follows 
that the ideal material is "one whose hardness is such that it can 
withstand the wear and tear of handling, and at the same time be 
impervious to the effects of moisture. Such a material is to be 
found in the metals but, as the cost of working them into the 
proper shape is considerable, some kind of wood is usually sub- 
stituted. 

Kind of Wood Used. If, then, wood is to be used, another 
qualification is to be added, namely, it should be easily worked. 
The best wood for the purpose is undoubtedly white pine. It can 
be obtained with a straight grain and free from knots. In choos- 
ing the wood, that which comes from the Northern States or 
Canada and has grown upon high ground, will be found to be the 
most satisfactory. Care should be exercised in the inspection of 
the wood, that it is clear, straight grained and free from knots. 

The straightness of the grain can be determined by the 
appearance of the sawn face. This should present an even rough- 
ness over the whole surface. It should be seasoned in the open 
air but preferably sheltered by a roof and be piled so that the air 
has free access to all parts of the stick. Kiln dried lumber is 
likely to be brittle and does not wc rk as easily as that which has 
dried more slowly in the open air. If the selection is to be made 
for any special work, the size of the timber should be proportioned 
to the place in which it is to be used, but for general pattern work, 
planks two inches thick will be found a convenient size. Lumber 
of this thickness can be properly dried and is also large enough for 
almost any pattern. It has the further advantage of not checking 
or cracking as easily as thinner stock. 

Pine, however, is soft and weak so that, if small and strong 
patterns are desired, a harder wood is usually employed. Mahogany 
is the most suitable for this purpose, and the same care should be 



PATTERN MAKING. 




exercised in its selection as in the case of pine. Genuine mahog- 
any, straight grained and free from defects, should be used and not 
the cross-grained bay wood that is often sold in its stead. 

Cherry is also extensively used and black walnut, beech, and 
maple to some extent. Black walnut is brittle and may crumble ; 
beech and maple are likely to warp. 

It may be stated, then, that, in the United States, white pine 
is the material commonly employed for pattern making. 

Warping and Twisting of Wood. Observation shows that if 
one side of a piece of wood is kept damp and the other dried, the 
former will expand and the latter contract so that the piece which 
was originally straight becomes curved as in Fig. 1. A common 

example of this is to be found in 
the planking of a board side- 
walk, where the upper surface is 
exposed to the drying effects of 
the sun, and the lower to the 
moisture arising from the ground. It requires more time under 
the same conditions for a large piece of timber to become dry than 
it does for a small piece ; because the moisture at the center has 
farther to travel before reaching the surface. Hence, small pieces 
cut from a large stick that has been seasoning, will not possess the 
same degree of dryness throughout their respective masses. If 
two of these pieces are fastened together the combination will warp 
as a result of the drying of the damper piece. It is well, there- 
fore, when making a pattern to get out all of the pieces and allow 
them to season for a while so as to avoid warping. 

Tools. The tools of a pattern maker's kit do not differ 
essentially from those of a carpenter who is doing first-class work. 
While it is impossible to give a list of all the tools that a pattern 
maker may find convenient, the following are the more essential. 

Saws, — cross-cut, rip, and miter. 

Planes, — jack, jointing, smoothing, compass, rabbet, and 
core box. 

Chisels, — firmer and paring of various widths. 

Gouges, — firmer and paring of various sizes, both concave 

and convex. 

Squares, — fixed and bevel. 



e 



PATTERN MAKING. 



Gages, Compasses, Trams, Calipers, Mallets, Hammers, Screw- 
drivers, Pliers, Spoke shaves, Brad awls, Oilstone, Scriber, Stand- 
ard and Contraction rules, and Clamps. 

Saws. Cross-cut and rip saws : these two kinds of saws are 




Fig. 2. 



as their names indicate, for cutting across the' grain and ripping 
with the grain of the wood, respectively. Their general appear- 

The difference between them is 
It is to be noted that that nearly all 



ance is shown in Fig. 2 
the shape of the tooth. 



i 
a 



Fig. 3. 



A 

Fig. 4. 



Fig. 6. 



woodworking tools do the cutting as they are moved away from 
the workman. The cross-cut saw has a tooth with the front or 

cutting edge inclined back from 



1 



f^xT^M^V^xN 



Fig. 5. 



the front, with the two edges 
beveled to form a cutting edge 
as shown at a of Fig. 3. The 
alternate teeth of the cross-cut 
saw are beveled on opposite 
sides as shown in Fig. 3. In 
addition to this, the alternate teeth are given a set as indicated 
by Fig. 4 at a and b. This set causes the saw to cut a wider slot 
or kerf in the wood than the back of the blade and thus prevents 
the material from pinching. 

The front edge of the teeth of a rip saw are at right angles 



PATTERN MAKING. 



to the line of the blade and are sloped back as shown in Fig. 5. 
They have no set as in the case of the cross-cut, but the points are 
broadened or swaged out by hammering as in Fig. 6. In this 
case the kerf is the width of the swaged points. 

A cross-cut saw can be used for ripping, but it is exceedingly 
difficult to use a rip saw as a cross-cut. 




Fit 



niter saws are used for sawing joints and miters across the 
grain. The teeth are usually very fine and the blade is stiffened 
by a heavy strip of metal along the back edge. It is illustrated 
by Fig. 7. 

Planes. The jack plane is used for removing the rough sur- 
face of the timber as it comes from the saw and thus preparing it 
for the jointer and smoothing planes. The stock of the plane is 
usually made of beech though it is sometimes of metal. The blade 




Fig. 8. 



or plane iron is of steel and is often made in two pieces : one the 
cutting blade and the other a strengthening piece or cover held to 
the former by a screw. The blade is held in position in the stock 
by a wedge which is usually made of wood. The blade should be 
ground slightly rounding on the corners so that they will not dig 
into the material for the pattern. The sharpening should always 
be done on the bevel face of the knife and not upon the flat sur- 



8 



PATTERN MAKING. 



face. This applies to all wood-cutting tools. After the iron has 
been sharpened the cover should be screwed on, the iron projecting 
a very short distance below it, as in Fig. 9. The whole is then 
put in the mouth of the plane and adjusted with the wedge, so 




Fie. 9. 



that the blade projects a short distance (about ^ inch) below the 
face of the stock. By looking along the face of the stock the 
amount of the projoction is seen and if it should be too much, a 
light blow on the top of the plane at the front end will drive the 
iron back. The amount of the projection determines the thick- 
ness of the shaving. 




Fis?. 10. 



Jointing Plane. This plane resembles the jack plane except 
that it is longer, and, therefore, gives a greater surface for straight- 
ening. It is shown in Fig. 10. The iron is ground the same as 
in the case of the jack plane, except that the rounding should not 
extend in for more than from Jg inch to | inch from the edge. 
The projection of the blade below the surface of the stock is also 
less than in the case of the jack plane. 

Smoothing Plane. This plane is shorter than either of the 
others. The blade should be sharpened and set like the jointer. 



PATTERN MAKING. 



9 



It is used for smoothing a surface rather than for trueing it. The 
plane is illustrated by Fig. 11. 

Compass Plane. This tool resembles the smoothing plane 
except that the working surface is convex instead of flat. It is 
used for smoothing concave surfaces where the curvature runs with 
the grain of the wood. It is shown in Fig. 12. 





Pig. 11. 



Fig. 12. 



Rabbet Planes are tools whose sole or working face has a 
shape to conform to the surface of the work to be done. They 
may, therefore, be of an infinite variety of forms, but the two in 
most common use are the narrow convex and the concave as illus- 
trated by Figs. 13 and 
14. The flat sole, as 
shown in Fig. 15, is also 
frequently added to the 
kit. The use to which 
these planes are most 
extensively applied is 
the making of mould- 
ings and fillets. 

Core-box Planes. The 
Fi^r. i3. woi-king out of cylindri- 

cal core-boxes is of 
every day occurrence in all pattern shops. This is done by first 
roughly shaping the work with a gouge, then bringing it to a 
circular shape with a core-box plane, and finally smoothing with a 
round-soled plane, Fig. 16. The core-box plane, Fig. 17, is con- 
structed upon the principle that two chords drawn from any point 
on the circumference of a circle to the opposite extremities of any 
diameter, form a right angle with each other. Such a plane is 




10 



PATTERN MAKING. 




shown in Fig. 17. The two sides forming the soles are at right 
angles to each other, and have a knife or plane iron in the corner. 
The method of using is as follows ; one-half the core-box is roughed 
out with the gouge as shown in Fig. 18. The points b and d on 
the edges of the groove are cut away as in the finished box and 

are made exactly to size 
throughout the entire 
length. Stock is left 
below for removal as 
shown by the solid line. 
The finished core is to 
correspond to the dotted 
semi-circle. The plane 
is so placed that the 
sides occupy the posi- 
Fi, r> !4 # tion shown by the two 

full lines a b and b c 
and these faces always kept in contact with the edges b and 
d. As the plane cuts away the surplus material its sides will 
occupy the positions indicated by the angles a' b' <?', a" b" c", 
etc., until the whole semi-circle has been cut out and the box 
is ready for smoothing. 
This plane can only be 
used when its sides are 
greater in length than 
the diameter of the core. 
Chisels. Two kinds 
of chisels are used by 
the pattern maker, the 
firmer (Fig. 19) and the 
'paring (Fig. 20.) The 
firmer chisel is intended 
for heavy work with the Fig ' 15 ' 

mallet, and to prevent splitting, the handle is usually set in a 
socket which is a part of the blade. The paring chisel is longer, 
lighter in the blade, and is sharpened with a keener edge and a 
longer bevel. Every pattern maker should possess an assortment 
of these chisels of widths varying from ^ inch to 1^ inches. 




PATTERN MAKING. 



11 




Fig. 16. 



Gouges. What has just been said of chisels applies equally- 
well to gouges, an example of which is illustrated in Fig. 21. 

Gouges are made with the 
bevel of the cutting edge 
on both the convex and the 
concave sides, though the 
former method is the more 
common. 

Squares. The square 
is one of the most impor- 
tant of the pattern maker's tools, for upon it depends the accuracy 
of his work. The usual form of try square is shown in Fig. 22. 
It is advantageous to 
have a number of these 
squares, of different 
sizes, in the kit. Those 
with blades 4 inches, 8 
inches, and 12 inches in 
length' will be found to 
be the most convenient. 
T bevels. As the 
wood of patterns is not always to be cut at a right angle, it is 
necessary that a tool should be provided for measur- 
ing acute and obtuse angles. The T bevel illus- 
trated in Fig. 23 answers this purpose. For con- 
venience in adjusting to small or cramped spaces a 
slot is cut in the blade. By means of this slot and 

„ a set screw the blade is 
c 

moved and clamped in any 

desired position and at any 
angle. 

Gauges. The gauge 
(Fig. 24) is used for draw- 
ing a line at a given dis- 
tance from and parallel to 
an edge of the wood. 
Fijr. is. The head #, slides on the 

stem b, and is held in any desired position by the thumbscrew e. 




Fie;. 17. 




12 



PATTERN MAKING. 




' ■■«■ |i ■, ■ 



Fig. 19. 




■ ;i-"i--'i ■ -■ l-'-'-- -i'l-. 



Fig. 20. 




Fig. 21. 




'I'l'l'l'l'l'l'l'l'l'l'l'l 
13 12 'll 



Fig. 22. 




Fig. 23. 



PATTERN MAKING. 



13 



In setting the gauge the adjustment is made so that the 
distance from the cutter d to the groove in the head a is 
equal to that at which the line is to be drawn. The 
groove is run along the edge of the wood and the cutter marks the 
desired line. Various forms of the gauges are in use, some having 
a scale showing the distance from the cutter to the groove, but the 
one shown is the ordinary form. 




Fie. 24. 




Fig. 25. 




Fig. 26. 



Compasses and trams. These instruments are used for 
describing the arcs of circles of given dimensions. The compass 
consists of two legs pointed at one end and pivoted together at 
the other. The pivot may be tight and the legs held in any 
set position by friction as in Fig. 25, or loose and held by a 
thumb screw in one leg, bearing against a wing or quadrant 
fastened to the other leg as in Fig. 26. Such compasses are 
sometimes provided with an adjusting screw, working on a spring, 
for facilitating the setting of the legs. Trams are merely large 



14 



PATTERN MAKING. 



compasses used where the distances between points are so great 
that the legs of the compass will not reach. Trammel points are 
fastened to a beam of sufficient length to enable them to be set at 
the desired distance apart. Such a tram is shown in Fig. 27. 
The body of the trammel is held to the beam in any position by 
the thumbscrews at the top. 

Calipers are made like com- 
passes but with legs so shaped 
that they can be used for measur- 
ing the inside or outside diame- 
ter of a circular body, or the 
distance between two points 
where it would not be conven- 
ient to use a rule. Figs. 28 and 
29 illustrate a pair of inside and 
outside calipers respectively. 
The points of the former are 
turned outward so as to come 
in contact with the inside sur- 
face of the work, while the re- 
verse is the case with the out- 
side calipers. 
Hammers and mallets. The ordinary form of hammer is 
that given in Fig. 30. Each kit should contain three or more of 
these tools of varying sizes, to be used according to the work in 
hand. The weights of heads range from 7 to 20 ounces. The 
mallet is used for driving the firmer chisels and gouges, and for 
striking surfaces that must not be marred. The head may be 
square, as in Fig. 31, or round. 

Small Tools. Screw drivers, Fig. 32, are used as their name 
indicates. As they are bought the end of the blade is usually 
ground on a straight bevel as in Fig. 33. The user will, however, 
find it advantageous to regrind it so that it has the form shown in 
Fig. 34. By so doing the tendency of the driver to slip out of 
the slot of the screw is lessened because the square side of the 
driver bears against the square side of the slot of the screw. The 
kit should contain several sizes of this tool with blades ranging 
in length from 4 to 10 inches. 




PATTERN MAKING. 



15 





Fig. 28. 



Fig. 29. 




Fig. 30. 




Fig. 31. 



16 



PATTERN MAKING. 



Pliers are used for holding small objects that cannot be con- 
veniently held in the hand ; for bending wire, etc. The common 
shape is shown in Fig. 35. 




Fig. 32. 

Bradawls are for the purpose of making small holes into 
which nails or screws are to be driven. An ordinary 
form is shown in Fig. 36. 

Oilstones serve to give a smooth, keen edge to 
the tool, after it has been ground. The Turkish 
stone is usually considered to be the best, but it is 
c 34. expensive. The stone ordinarily used in this country 
comes from Arkansas . A convenient size will measure 
6 inches by 1| inches or 8 inches by 2 inches. These should be 




Fig. 35. 




Fig. 86. 




Fig. 37. 



mounted in a case with a cover to protect them from the dust 
when they are not in use. It is also desirable to have a piece of 



PATTERN MAKING. 



17 



leather on the top of the cover for a final whetting when an 
especially sharp edge is required. 

Scribers or Scratch awls (Fig. 37) resemble bradawls except 
that the end is pointed. They are used for marking on wood and 
laying out work. 

Rules. For ordinary measurements the pattern maker needs 
a two-foot folding rule similar to those carried by carpenters and, 
other workmen. For laying out and taking the dimensions of 
patterns a shrinkage rule must be used. When a mould is filled 
with molten metal the temperature of the latter is very high, and 
as it cools and solidifies, it contracts. The pattern maker must, 
therefore, compensate for this by adding to the size of the pattern. 




Fig. as. 
In order that this may be done and exact relations be maintained 
for all dimensions, a shrinkage rule is used. This rule is marked 
off exactly like an ordinary rule, but if the two are compared, the 
former will be found to be about -| inch longer for each foot of 
length. These rules are usually made of a single straight length 
of beech or boxwood 24| inches long and are graduated as though 
they were exactly 2 feet. In using the shrinkage rule, the work- 
man proceeds as though he were using a standard rule, and when 
the pattern is completed it will be found to be 12i inches long for 
a 12 inch casting. All other dimensions will be larger in the same 
proportion. 

Clamps. Every pattern shop should be equipped with a 
number of clamps or handscrews similar to that shown in Fig. 38. 



PATTERN MAKING. 



These clamps are adjustable through wide ranges and are used for 
holding pieces together that are being glued or for other purposes. 
A special form is the C clamp, shown in Fig. 39. 




Fig. 39. 




Fig. 40. 



In the use of all cutting tools, especially paring chisels, 
gouges, and planes, particular attention should be paid to the grain 
of the wood. Where the grain does not run exactly true with 
the piece as in Fig. 40, the plane or chisel should be moved so as 

to cut in the direction of the arrow. 
This smooths down the grain and the 
tool has a tendency to run out. But, 
if the cutting is done in the opposite 
direction the tool tends to dig into 
the wood, taking a shaving of increasing thickness and finally 
causes splintering. 

machinery. The machinery used in a pattern shop varies 
with the size of the establishment and the number of" men 
employed. It is not necessarily the same as that in an ordinary 
wood-working shop but it is of the same character. The one 
machine that is indispensable is the lathe. 

The Lathe. This useful machine (Fig. 41) should be care- 
fully made and rigid in all its parts. As the pattern shop is 
usually upon an upper floor, where the machinery must be placed 
upon joists, it is essential that the lathe itself should possess all 
the requisites of rigid construction, in order to avoid the vibration 
that would otherwise result from running it at a high speed. The 
legs and bed should be of iron and the head stock carefully fitted 
and firmly bolted in place. The spindle should be of steel and 
carefully fitted in phosphor bronze bearings. When there is 



PATTEKN MAKING. 



19 



only one lathe in a shop, it should be of such size that it can swing 

pieces at least 12 inches in 
diameter and 6 or 7 feet 
long. The headstock 

should be made reversible 
and the face plate be made 
to overhang the bed, thus 
making it possible to turn 
work of large diameter. 
Or, better still, the spindle 
should be extended through 
the outer box and fitted for 
the attachment of a face 
plate. The lathe should 
be driven by a cone pulley, 
that is made as light as 
possible, and whose size 
should be such that a speed 
of at least 1,400 revolu- 
tions per minute can be 
obtained when the belt is 
driving on the smallest 
pulley of the cone. This 
will give a rate of revolu- 
tion, when the belt is on 
the largest step of the cone 
of about 350 per minute. 
Closely connected with 
the lathe are the chucks 
for holding the work. The 
end of the spindle should 
be cut with a screw thread 
upon which a face plate 
may be screwed and it 
should also be made hol- 
low and tapering for the 
reception of a fork center. 

The latter is used for driving work that is run upon the dead cen- 




20 



PATTERN MAKING. 



ter of the tailstock and also serves as a live center, carrying one- 
half the weight of the piece. It is shown in Fig. 42. Another 
simple method of driving is called the screw drive. This is a 
chuck cut with an internal screw to fit that on the lathe spindle 




bfv^ 



i i | i|i il I ui, 

II 1 I in I II 

I' I M HI I K 
I I', II HI in 

i ' i i 1 1 i i i 1 1 



1 1 ■ ■ i i 1 1 • ; i • 1 1 1 



Fig. 42. 



Fie. 43. 





Fie. 44. 



and having a coarse wood or machine screw projecting from the 
front face. It is used to hold light work that is short and of small 
diameter. It is shown in Fig. 43 and it will be seen that the 
piece to be operated upon is simply run upon the screw. 



PATTERN MAKING. 21 

For work of large diameter face plates are necessary ; these 
are usually made of wood held by screws to a flanged coupling 
which is screwed upon the spindle. The plate itself may be a 
piece of board for small diameters or it may be built up as shown 
in Fig. 44. 

The tool rest is usually T-shaped and made to slide freely 
along a groove at the front of the lathe bed. It should be easily 
and quickly fastened in position either by a wedge or cam involv- 
ing only a single blow from a hammer or one motion of the hand. 

On long lathes and in shops where 

columns and pipes are to be turned, it is 

I well to provide a sliding carriage in which 

f\ the tool is fastened. The carriage may 

be moved by a rack and pinion parallel 

to the center line of the lathe. This makes 

it possible to do straight work more rapidly than can be done by 

hand tools. 

Hand tools. When a piece of work is put in the lathe the 
roughing cut is invariably taken with a gouge. The turning 
gouge d'ffers from the one already described in that it is heavier 



J_ 




Fig. 46. 

aiid is ground somewhat differently. In grinding a turning gouge 
it is cut away more on the sides than at the center so that the 
angle of the bevel may be the same. In using this tool the hand 
rest is set so that it clears the revolving work by about a half an 
inch. The gouge is held in both hands, one grasping the blade 
near the hand rest and the other the end of the handle. In tak- 
ing a roughing cut the gouge should be tilted to one side, the 
advancing edge being the lower. If this precaution is not taken 
the tool will tend to rip into the work. The position of the gouge 
is illustrated by Fig. 45. 

The gouge may be and is extensively used for finishing but 
the skew chisel, Fig. 46, does better work although it requh^es more 



22 PATTERN MAKING. 

skill to manipulate. It is held very slightly inclined to the work 
and is fed in the direction of the inclination which should always 
be toward the short edge of the blade. 

For finishing, an ordinary square chisel is frequently used.. 
With this tool as well as with the gouge and skew chisel the hand 
rest should be set so that its upper surface is about level with the 
center of the work. The square chisel is held level while the 
other two are given a slight upward inclination. The square 
chisel thus becomes a scraper and should not be required to 
remove very much material. The shape of this tool is sometimes: 
modified so as to have a rounded or angular cutting edge. 

The grindstone. Second in importance to the lathe in the 
power-driven tools of the pattern shop is the grindstone. A good 
close-grained Huron stone of about three feet in diameter, when 
new, is suitable. The stand should be provided with ample facil- 
ities for keeping the stone wet. A very satisfactory arrangement 
is a ^-inch water pipe terminating in a T-head with valve for con- 
trolling the flow. Shields are sometimes used to prevent the 

water from spattering and a cast iron 
sink is placed underneath. The grind- 
stone ought not to be neglected but the 

bearings should be kept well lubricated 
Fig. 47. . 

and the outside true. No stone can be 

found of an absolutely uniform hardness, and, as the pressure and 

surface presented by the tool varies from second to second, the 

stone soon loses its cylindrical shape. It should then be turned 

true, an old file being an excellent tool for the purpose. 

In using the grindstone it is better to stand so that the stone 
runs away from the cutting edge as shown in Fig. 47. This 
method is less likely to cause hollows to be cut in the stone and is 
also easier. After grinding, the feather edge rolled back on the 
cutting edge should be wiped off on the hand or piece of pine and 
the final sharpening be done on an oil stone. The flat face of the 
tool should be rubbed lightly over the stone to remove the last 
traces of the feather edge and then keenness added by rubbing the 
bevel. The finishing touch may be put on by stroping the tool on 
leather. 

Saws. The lathe and the grindstone are the two essentials- 




PATTERN MAKING. 



23 



of a pattern shop, but it is very desirable that they should be sup- 
plemented with a circular saw table. This table may have one or 
two arbors. If there are two, one should carry a rip and the other 
a cross-cut saw. The latter is the most convenient as such tables 
are made so that either saw can be instantly raised to the cutting 
position or as quickly lowered. The table should also be provided 
with an adjustable and removable gauge or fence so arranged that 





Fig. 48. 

it may be easily taken away ; thus leaving the whole upper surface 
of the table clear. It should also be possible to set it at any angle 
for beveling, gaining, etc. A convenient table of this kind is 
shown in Fig. 48. The size of saw that is best suited for the 
ordinary pattern shop is about 10 inches in diameter and should 
be made to run about 2,500 revolutions per minute. 

The next tool to be placed in the pattern shop is the band or 



24 



PATTERN MAKING. 



jig saw. These two types of saw are intended for doing about 
the same class of work. They may be used to cut scrolls and 
curves and thus save much necessarily slow handwork. The band 
saw has the advantage of more rapid and smoother cutting while 




Fig. 49. 



the jig saw can be used on the interior of closed curves. It is 
however, possible to use the band saw for this work by cutting 
through the solid material and then glueing a thin strip in the 
kerf to close the opening thus made. In band saws the pulley 



PATTERN MAKING. 



'25 



wheels should be large, light, and carefully balanced. They should 
be large so as to prevent breakage due to the bending of the saw 
to a small radius ; they should be light so that their momenta may 




Fie. 50. 



not cause over-running, producing a buckling and breakage ; and 
they should be balanced to avoid jar and a strain on the saw when 
the bearings become worn. The cutting speed of the saw should be 



26 



PATTERN MAKING. 



about 3,500 feet per minute. Fig. 49 illustrates a well-designed 
saw. 

A convenient width of saw and one which will answer for all 
general purposes is |-inch. As breakage is apt to occur, the pat- 
tern maker should be able to repair the saw by brazing ; a kind of 
work that will be described later in the course. 

The jig saw (Fig. 50) works more slowly than the band for 
the two-fold reason that the speed is less and the cutting takes 
place only during the downward stroke. The usual method of 
construction is to fasten the upper works to the ceiling, leaving the 





BBS , "' -4 




Fig. 51. 



whole surface of the table clear for any size of work. This upper 
portion consists of a spring and guide to which the saw is attached 
and by which the up stroke of the latter is made. Beneath the 
table there is a crank and connecting rod driving a crosshead 
to which the lower end of the saw is fastened. The means of 
attaching the saw to the upper slide should be in the form of a 
hook or some other simple contrivance so the blade may be easily 



PATTERN MAKING. 



27 



disconnected for placing or removing the work. The speed of the 
machine should be about 1,100 strokes per minute and the length 
of stroke should be about 6 inches. The width of saw may vary 
from ^-inch to |-inch. 

Where one saw for scroll work is installed it is usually the 
jig or fret saw. 

Planing Machine. This is a valuable machine but is one 
that does not find a place in every shop. It is used for dressing 
lumber to convenient thickness. The ordinary surface planer will 
not, however, take the twist out of timber, but merely smooths 




Fie. 52. 



and brings it to an even thickness. It works rapidly and its knives 
should be driven at a speed of about 2,500 revolutions per minute. 
A convenient form of this machine is shown in Figs. 51 and 
52. It is so arranged that it can be converted from the planer 
(Fig. 51) to the jointer (Fig. 52) by merely raising the table. 
The jointer can be used to take the twist out of material that is 



28 PATTERN MAKING. 

warped and the planer afterwards put into service for bringing it 
to the thickness desired. 

Universal Trimmer. This tool (Fig. 53) is one that, of late 
years, has become very popular in the pattern shop. It will cut 
any sides or ends within its capacity, and an end that would take 
from ten to fifteen minutes to square properly with a square and 
chisel can be finished in as many seconds with this machine. The 
cutting is done with remarkable smoothness and requires no sand- 
papering to prepare it for varnishing. The machine is operated 
by hand. The table is fitted with gauges and fences so that the 
knives can be made to cut at any angle. The power is applied by 
means of a long handle to which a pinion is fastened ; the latter 
meshes with a rack on the plate carrying the bevel knives which 
are moved to the right or left according to the direction of motion 
of the handle, the work being held against the guides at the side 
of the machine. 

riethod of floulding. As has already been said, it is neces- 
sary that the pattern maker should have some knowledge of mould- 
ing in order that he may construct his patterns so that they can 
easily be removed from the sand. A brief description of the gen- 
eral method employed will suffice. Ordinarily a casting is made 
in a flask composed of two parts, each containing its complement 
of sand. The upper part is called the cope and the lower part the 
nowell or drag. The pattern is usually made in two pieces which 
part along the line separating the cope and drag. Thus in Fig. 
54 the pattern separates with the flask on the line A B and when 
so separated the cope is turned upside down and the portion of 
the pattern C is lifted out. The part D is lifted out of the drag 
in the same way. 

In the case of hollow objects, the internal cavity is formed by 
cores which rest in cavities of the sand made by the pattern. 
Fig. 55 represents a section of a flask with the mould made and 
core set for the casting of a hollow cylinder. The pattern was 
parted along its center line as before and the sand rammed in 
both cope and drag. Then after its removal the core A is set in 
position, resting upon and filling up the spaces x and y made by 
the core prints of the pattern. Therefore, when the metal is 
poured it fills the open space around A, forming a hollow cylinder. 



PATTERN MAKING. 



2& 





Sfejiiiiiimiiiim iM 



Fig. 53. 



30 



PATTERN MAKING. 



Patterns from Drawings. As already explained the pattern 
maker must understand working drawings in order to make 
full size drawings from them or construct the patterns directly. 
In all drawings that he receives the dimensions given will be those 
of the finished piece. That is to say, the drawing is a representa- 
tion of the piece as it will be when completed. It has already 
been noted that the pattern maker must make his pattern larger 
than the actual piece in order to allow for the natural shrinkage 
of the casting in cooling. This increase of size is, however, 
allowed for by the shrinkage rule with which he takes his meas- 
urements. But if the piece is to be finished in the machine shop, 





Fis. 54. 



Fig. 55. 



an additional amount must be added to the pattern in order to 
provide the metal that is to be removed. The amount that is to 
be so added is, to a certain extent, though not wholly, independent 
of the size of the piece. For small articles whose longest dimen- 
sion does not exceed three or four feet an addition of \ inch to 
the surface to be finished is usually sufficient. For larger dimen- 
sions it may be necessary to add as much as ^ or | inch though 
very rarely more than this. In making this allowance it is also 
well to bear in mind the inclination of the piece to warp in cool- 
ing. Where the thickness of the metal varies to any great 
extent there is a greater liability to warp than if a uniform thick- 
ness prevails throughout the whole. Hence, in such cases a greater 
allowance must be made for the finishing. 

On small pieces and where the moulding is carefully done it 
may be possible to make smaller allowance than i inch, but as a 
general rule sufficient metal should be put upon the casting so 
that the cutting tool of the finishing machine may cut well below 
the surface and not become dulled by the sand and hard scale on 
the outside. 

Simple Patterns. The simplest patterns are naturally those 
which are made in one piece and which require no coring, although 



PATTERN MAKING. 



31 



the casting may itself be hollow. The first thing which the pat- 
tern maker should decide in commencing a pattern is the way in 
which it is to be removed from the sand and where the parting 
line should be if there is to be one. As an example of a simple 
pattern of one piece made without a core, the stuffing-box gland 
of Fig. 56 is a good example. 

It must be understood that in order for a pattern to draw out 
of the sand it can have no re-entering parts that can catch the 
sand as it is lifted. In the gland under consideration this is the 
case. It is readily seen that if the pattern of such a gland were 
to be bedded in sand as shown in the engraving there is no reason 
why it should not be lifted out in the direction of the arrow with- 
out disturbing any of the surrounding 
sand. The finished gland is to be 
cut to the contour of the dotted lines. 
It is important for these to be straight 
and form right angles with each other. 
It has already been explained that the 
pattern must be made larger than the 
finished contour to allow for the 
metal to be removed by finishing. 
36 by the difference between the 
There is another allowance, however, 

It will 



ET™f 



.d* 



Fi£?. 56. 



This is shown in Fig. 
full and the dotted lines. 

that should be made. This is called the draft of a pattern, 
be seen that if the diameter of a pattern at a were to be the same 
as that at b, the latter point would drag over the whole length of 
the sand until it reached the former point. As the sand is held 
together very lightly this dragging would be likely to dislodge 
some of the particles and make it necessary to mend the mould. 
In order to avoid this, the diameter at a is made slightly greater 
than that at b so that the body of the gland is tapering and, the 
moment it is started out the whole surface from a to b is clear of 
the sand and can be removed without injury. This difference in 
the diameters at a and b is called the draft of a pattern. The 
amount of draft depends upon the length of the part that is to be 
drawn out of the sand. A convenient measure is to increase the 
diameter \ inch for each foot of length or add -^ inch to each foot 
-of flat surface. 



32 PATTERN MAKING. 

In this case there must also be an allowance for draft on the 
inside between c and d and also at the edges of the flange at e and 

/• 

The pattern shown is entirely embedded in the sand of either 

the cope or drag though it would usually be moulded in the latter. 
It is quite possible, however, to have a pattern in one piece 
imbedded in the sand in both cope and drag. Such a pattern is 
to be found in the journal brass used on railroad car axles, as 
shown in Fig. 57. 

Hereafter no reference will be made to the allowances for 




Fig. 57. Fig. 58. 

finish and draft on patterns, it being understood that the former 
must always be present where the surface is to be machined and 
the latter where a vertical surface is to be drawn out of the sand. 

In Fig. 57 let A B be the parting line between the cope and 
the drag. The pattern is first placed face down on the moulding 
board the drag is placed around it and the sand rammed home. 
The drag with the pattern is then turned over, the cope put on 
and the sand rammed. Then on lifting off the cope, the sand 
lying in the curve C E D is lifted with it, allowing the pattern to 
be removed from the sand of the drag without disturbing anything. 

One more example of one-piece patterns will be given, Fig. 
58 is a small handwheel that is usually made solid. It will be 
seen, however, that if the pattern were to be rammed in the sand 
with the parting line between cope and drag on the line C D it 
would be impossible to remove it. It may, however, be rammed 
in this way and then the sand cut and removed down to the center 
line a b, after which the cope may be but on and rammed. This 
makes the parting line between the two run on C c b a e- D, so 
that the pattern is readily drawn from the sand of the drag after 
the cope has been removed. 



PATTERN" MAKING. 



33 




The pattern maker should therefore be familiar with foundry 
work in order to obtain the best results. 

Cores. Cores are used for forming the hollow spaces inside 
of castings and must be provided for by the pattern maker. The 
simplest and at the same time, the most common core is a straight 
cylinder. If by reason of its small size it is desirable to core the 

hollow through Fig. 59, the pattern 
would be made solid as shown, 
and two core prints a and b be 
placed upon either end. These 
prints should have the shape of 
a truncated cone whose larger 
diameter is \ inch smaller than the 
finished hole through the gland. 
The height of the print would be 
dependent upon the diameter and 
length of the core, and ranges from 
a projection of 1 inch to 6 inches. 
In Fig. 59 the print a is loosely 
attached to the pattern for reasons that will be explained later. 

Cores are used when the shape of the casting is to be such 
that the pattern cannot be made to leave its own core and where 
the green sand core, if left, would probably be washed away by 
the flowing molten metal. 

Core Boxes. Round cores are usually made in half-round 
boxes cut on a plane through the axis of the cylinder and for small 
cores held together by dowel pins. For the larger sizes of 3 
inches or more in diameter single half boxes as in Fig. 60 are 
used. The core sand is packed in the box, turned out on the 
table and two pieces pasted together making a round core of the 
diameter of the box. 

It is customary in most foundries to have a complete set of 
these coreboxes ranging in size from 1 inch in diameter up to the 
largest size for which the ordinary work of the establishment may 
call. The boxes are made long enough so that the cores can be 
cut to any desired length. 

In the making of such a corebox, the box in which the groove 
is cut is first gotten out and a semi-circle scribed on each end with 



34 



PATTERN MAKING. 



lines connecting the extremities of the same, drawn across the 
face of the block. The groove is first roughly cut out with the 
gouge and then finished with the corebox plane, or with the 
gouge, using the square as shown in Fig. 61 to test the accuracy 
of the work. The curve is then sandpapered, varnished and the 
ends closed with the pieces a and b as shown in Fig. 62. 





Fig. 60. 



Fig. 61. 



ill 



For cores of large diameter the boxes are built up as shown 
Fig. 63. The corners of the projecting pieces are then 

removed with the gouge and the 
box finished to the guide lines with 
the corebox plane as before. 

If, however, the box is so large 

that the diameter is greater than 

the side of the corebox plane as in 

Fig. 64 so that a bearing cannot 

be obtained upon both sides of 

the groove at the same time, it 

will be necessary to work as close 

as possible to the guide lines with 

a gouge using the square for 

testing the work as in Fig. 61 

and then finish with a round soled 

plane, Fig. 16, whose radius is a 

little less than that of the groove 

to be cut.. 

Sometimes, as already stated, two halves of a corebox are 

made and the sand rammed into the hole thus formed from the 

end. In such cases the two parts are brought into an accurate 

alignment by means of do well pins. In one half there is a 



Fig. 62. 



PATTERN MAKING. 



35 



1 - i: 


1 , / 


s 1 IV 


\l 


IV 


\l 


i ,' 


^ 1 


i •' 











Fig. 63. 



dowel pin that is adjusted to fit accurately in a corresponding hole 
in the other half as shown in Fig. 65. There should never be less 
than two of these pins and the number should be increased with 
the size of the corebox or pattern, since patterns are held together 
in the same way. These pins are usually of hard wood about f 
inch in diameter and are bought in lengths from which the indi- 
vidual dowels are cut. They 
should be driven firmly home, 
glued into one piece and have 
a accurate fit in the other 
half. The point should be 
beveled so as to enter the 
hole readily and the whole 
pin should be from i inch to 
| inch in length. 

In locating dowel pins it 
is, of course, very necessary 
that the pin and hole should 
be accurately placed. This 
can be done by measurements 
but the simplest way is to lay 
an ordinary pin on the face 
of one half with the head 
where it is desired to locate 
the center of the dowel. Then 
by adjusting the parts and 
pressing them together the 
pin will indent the wood on 
each and thus mark the point 
at which the holes are to be 
bored. 

Two Part Patterns. The greater portion of cast iron and 
brass work is so designed that it is necessary to make the patterns in 
two pieces. Small patterns may be made of a single piece of wood 
though warping is likely to occur after they have been used for a 
time and have been subjected to the alternate moisture of the 
moulding sand and the extreme dryness of the pattern loft. 
Large and expensive patterns are, therefore, invariably built 




36 



PATTERN MAKING. 



up of thin pieces that are glued and nailed together properly. 

An example of a simple two-part pattern is given in Fig. 66 

which represents a section of cast iron pipe with flanges at each 

end. The pattern may he solid, or, if it is of large size, the 



U 




Fig. 66. 






1 




1 






1 






^-. 




1 ,' 








, 




1/ 












1 / 










1 


1 / 1 


1 / ',1 


1 1 



Fig. 67. 



Fig. 68. 



Fig. 69. 



huilding up may be so arranged that the interior is hollow as 
shown in the section given in Fig. 67. In making such a pattern 
the pieces used for building up are cut approximately to size, glued 
and nailed together. Each half is made separately until two 
pieces, each of a section like that shown in Fig. 68 are obtained. 
The dowel pins are then driven firmly into one, the holes adjusted 
in the other and the two parts held together by staple dogs driven 
in at the ends as in Fig. 69. The head and tail-stock centers of 
the lathe are then set on the parting line and the whole turned to 
a cylindrical shape as though it were a single solid block. After 
turning, the flanges are cut out and nailed or glued in position. 
The projections beyond the flanges are the core prints upon which 
the core, forming the exterior of the pipe, rests. These prints are 
of the same diameter as the core and the inside diameter of the 
pipe. Hence, when the metal is poured, the casting has the form 
of a pipe with flanged ends as desired. 

The method of moulding such a pipe will be treated in con- 
nection with instruction on foundry work. It will, of course, be 



PATTERN MAKING. 



37 



impossible in any work on pattern making to give detailed instruc- 
tions for the making of every pattern that may be called for ; but 
the instructions given for the making of a few of the more common 
articles will serve as a guide. 

Face Plate. It is sometimes advisable to use cores even if it 
is quite possible to construct the pattern so that it would core 
its own holes. This is the case where it is desired that the faces 
of the casting should be smooth and as true as possible without 
expensive machine work. Such a case is found in the face plate 
of an engine lathe, a drawing of the finished product being shown 
in Fig. 70. 




Fig. 70. 

It will be readily seen that this casting could be put in the 
sand, rammed home, and withdrawn leaving the sand standing 
where the holes are located. 

The trouble that would arise from this method would lie in 
the fact that when the metal is poured and allowed to flow about 
the fragile projections that are left to form the holes the sand 
would be washed away, so that the holes in the casting would be 
irregular and much smaller than those in the pattern. The quality 
of the iron is injured by the sand which is caught on the upper 

surface. 

For these reasons the holes should be cored, as the core 
sand is firmer and better able to resist the washing action of the 
flowing metal. 



38 PATTERN MAKING. 

The pattern for such a face plate should, therefore, be made 
as follows : First it is to be noted that the metal must be thicker 
than the finished piece on the surfaces. Having thus deter- 
mined the thickness of the pattern on the face, the disc should 
be built up of from four to sixteen segments according to the size 
of the plate. If the diameter lies between 30 and 42 inches, 
sixteen sectors should be cut out each filling an arc of 45° so that 
when eight are placed edge to edge they will complete the circle. 
The thickness should be a little more than one-half the completed 
thickness of the pattern disc and they should be laid up so as to 
form two layers, breaking joints with each other as shown in Fig. 
70. When this disc is formed the hub should be glued and 
screwed in position, this also being built up of pieces glued together. 
The rim is then built upon the disc. This is done by cutting 
segments of ^ inch or | inch stock and glueing them in a circle of 
the proper diameter. In building up to the proper height care 
must be taken that no joints of two adjoining layers coincide but 
that all joints are broken. 

The pattern now consists of the disc with the rim and hub in 
position but larger than they should be. It is, therefore, placed in 
the lathe and carefully turned over its whole surface, each part and 
thickness being brought to the shape and dimensions of the com- 
pleted pattern. It will be found convenient, however, to cut all 
angles square, leaving the fillets to be put in later. 

The next step is to put in the ribs. It will be unnecessary to 
form these out of built-up material, for each may be cut from a 
single piece. 

They should be carefully fitted to form a close joint with the 
rim, the disc, and the hub, before they are glued in position. 
When this is done, all the angles formed by the rim, spokes, and 
hub with each other should be carefully filleted. That is to say, 
a quarter curve should be placed in these corners so that there 
may be no sudden change in direction of the surface of the casting 
which may cause weakness. 

These fillets are made in various ways ; the cheapest and most 
unreliable is putty which depends upon its own adhesiveness and 
a film of varnish to keep it in position. This is sometimes 
employed but is not to be recommended. Beeswax used in the 




PATTERN MAKING. 39 

same manner is better but is not good. Next comes a wooden 
fillet cut as in Fig. 71, nailed and glued in position. This forms 
a substantial fillet, and if properly put in, will last as long as the 
pattern. Metal fillets of the same shape are also sold and serve 
the purpose equally as well if not better than wood. The radius 
of curvatures of these fillets varies from | inch up, dependent upon 
the size and weight of the casting. 

After the fillets are in position it remains 
to provide for the coring of the holes This 
is done by first laying out upon one face 
of the pattern the location and size of the 
holes. It is upon the points thus located that Fig. 71. 

the core prints are placed. Before this is done 
it must be decided which side of the casting . is to be made 
uppermost. 

Where a large, flat surfaceis to be given a finish it is desir- 
able that the metal should be as clean and free from sand and 
blowholes as possible. As the iron has a greater specific gravity 
than the sand of the mould, all particles of sand that may be 
washed away and all gases generated, rise to the surface of the 
molten metal. Those imprisoned by the cooling of the latter 
form the dirt and blowholes that disfigure the completed casting. 
In such a casting as the faceplate under consideration it is desir- 
able, then, that the face should be upon the lower side when the 
metal is poured. For the sake of convenience in setting the cores, 
the prints are, therefore, put upon the face and make their 
impress in the sand of the drag. They should be glued and nailed 
in position after the pattern itself has been sandpapered. The 
core prints for the hole through the center are also put on in the 
same way. 

Glueing. In describing the method followed in the construc- 
tion of the faceplate pattern, it was directed that certain parts 
should be glued together. 

First get a good quality of glue, then keep it cool, in a clean 
box and protected from the dust. The glue-pot in which it is to 
be prepared should always be double ; that is, there should be an 
outer pot partly filled with water into which the smaller inner 
pot used for the direct preparation of the glue should be placed. 



40 PATTERN MAKING. 

This is to avoid burning, since if the glue is overheated its adhesive 
qualities will be greatly impaired. This cannot happen if set in a 
pot of boiling water whereas it can hardly fail to occur if the heat 
of the fire is applied direct. The most convenient form of pot is 
one where the water in the outer pot is heated by steam. 

When the glue is to be used, it should first be washed in cold 
water and then broken up with a hammer. After being placed in 
the inner pot it should be well covered with clean water. As it 
heats stir it from time to time with a stick and throw away any 
scum that may rise to the surface. 

Glue joints may be made with the truing plane, a larger one 
called a jointer, or, if the piece comes within the capacity of the 
machine, on the universal trimmer. The joint should be very 
carefully made so that the two pieces of wood are in contact over 
their whole surfaces. When these have been properly prepared 
the glue is spread over them and they are pressed tightly together. 
Where the surfaces are large or long it is well to move them to 
and fro over each other before the glue sets in order to work out 
all the air and superfluous glue. The pieces should then be 
held together by clamps or weights until the glue has thoroughly set. 

Sometimes a difficulty will arise in the case of large surfaces 
of thin material. When the glue is applied it moistens and there- 
fore has a tendency to expand the surface upon which it is placed, 
causing the edges to curl up and pull away from the opposing 
piece which has a tendency to move in the opposite direction. 
This may be diminished by moistening the back of these thin 
pieces with water from the outer kettle. 

When it is desired to have the glue set more quickly than it 
would in its natural condition, the addition of whiting will accom- 
plish it. The greater the quantity that is added the more rapid 
will be the setting but it must be borne in mind that this forcing 
of the setting weakens the glue. 

In cold weather the precaution must be taken to heat the 
pieces before applying the glue, else the latter may be prematurely 
chilled and fail to set. 

The time required for a well-made joint to set is from one and 
a half to three hours, dependent upon the quality of the wood and 
the thickness of the glue. 



PATTERN MAKING. 



41 



Where the pieces are held by glue alone and work is to be 
done upon them in the lathe or at the bench, it is well, if possible, 
to allow the glue a whole night to set before proceeding with such 
work. 

Engine Crank. A more simple pattern than the one last 
described is to be found in 



the engine crank illustrat- 
ed by Fig. 72. As before, 
if the face is to be finish- 
ed it should be cast with 
that side down. The con- 
struction of the pattern is 
very simple and consists of 
cutting out the several 
pieces that go to form the 
body and boss of the 
crank, then nailing and 
glueing them together to 
form the pattern. After 



c 



3 




Fig. 72. 



this has been done and the pattern has been carefully sandpapered, 
the cores are attached and set on with single dowel pins located 
at their centers. 

Tee Pipe connections are common features of pattern work 
in nearly all shops. The size of the connection determines 
whether the body of the pattern is to be of a solid block of wood 
or is to be built up. In the construction of the T shown in Fig. 
73 either method may be followed. The body and branch are 
prepared and turned separately and the flanges put on in exactly 
the same manner as that given in the description of the making of 
flanged pipe pattern Fig. 66. The pattern must be made in two 
parts. The union of the branch with the main body may be made 
in one of two ways. It may be cut away on a circle as shown in 
Fig. 74 or a V-shaped slot may be cut in the body and the end of 
the branch fitted into it. The latter, if well made, is the better 
way as a more substantial job can be done. Either method leaves 
an angle on the line of unison a b c which should be eased off by 
the use of a fillet. 

The core prints on the T are square at the ends because they 



42 



PATTERN MAKING. 



Fig. 73. 




draw out sideways from the sand and the flasks are apart when the 
core is placed in its position. 

The core-box is made like those of circular cores 

already described and the 
two parts of stem and 
branch are easily fastened 
together. The most sat- 
isfactory way will be to 
make the box for the stem 
and then cut the side inlet 
to its edge and finally fasten 
the branch on the side with 
glue and nails, giving it 
sufficient length to reach 
to the end of its own par- 
ticular core print. 

The patterns for elbows, 
bends, and angle tees may 
be made in exactly the 
same way. 
Pulleys. Almost every patternshop is called upon, from time 
to time, to make patterns for pulleys. There are two ways in 
which this can be done ; one is to build up a rim of wood and put 
in the hub and spokes thus making a complete pattern ; the other 
is to make a skeleton pattern consisting of the hub and spokes and 
an independent iron rim. This rim may be used for obtaining any 
breadth of face that may be desired. The former method is rarely 
employed as it is expensive and with it any variation in the width 
of the rim of the casting is made with difficulty. 

Where the iron rim is to be made no great care is necessary 
in the building up of the original wooden pattern. It must be 
remembered that before the final casting is obtained, two shrink- 
ages will take place ; first, the shrinkage of the original casting 
from which the iron ring is turned and then the shrinkage of the 
casting made from this pattern. In addition to this, there must 
be the allowance for turning the ring inside and out and the turn- 
ing of the outside pulley rim. Suppose the pattern is to be made 
for a pulley 2 feet in diameter. The usual allowance for a single 



Fkj. 7-t. 



PATTERN MAKING. 43 



shrinkage is made by the shrinkage rule, to which must be added 
as much more. Thus in the case of the above pulley, the diame- 
ter of the wooden pattern becomes 

24i -f I ■ = 24i inches. 

As I inch must be allowed for the outside finish of the iron 
ring and as much more for that of the rim of the pulley, the out- 
side diameter of the original wooden pattern is 25 inches as meas- 
ured with a common rule or 24| inches as measured with the 
shrinkage rule. If the final thickness of the rim is to be | inch, 
this, with the allowance of ^ inch for the turning of the inside of 
the iron ring makes the inside diameter of the wooden ring. 

24 1 ■ ■ 2 (| + i) — ^\ i ncnes as measured by the common rule 

or 23 inches (about) as measured by the shrinkage rule. The 
original pattern should then be built up of segments nailed 
together until a width of about 4i or 5 inches is obtained. It is 
then put in a lathe and turned to the proper diameters and without 
any draft. This pattern is then sent to the foundry and a casting 
made at, least 6 1 - inches wide. This can be done in the foundry 
by first ramming the sand about the pattern and partly drawing 
the pattern and then ramming again to the new level. 

The casting thus obtained is then turned to the dimensions 
called for by an ordinary pattern; that is to say, the shrinkage 
rule measurements would leave it 23^ inches diameter on the 
inside and 24^ inches on the outside, permitting a final finishing 
of the outside of the rim of the pulley to a diameter of 24 inches. 
When this is done two -| inch holes should be drilled near one 
edge of the rim and diametrically opposite each other, into which 
hooks may be inserted for drawing the pattern. This ring should 
also be turned straight and without any draft. 

The spokes are usually made with a wooden pattern, which 
has a dowel-pin hole on each side at the center for attaching the 
hubs that are loose, the object being to be able to change their 
length and diameter to suit the width of the rim and the diameter 
of the shaft upon which the pulley is likely to be placed. 

The spoke is usually curved except on very small pulleys. 
The reason is that there is often a greater thickness of metal in 
the hub and spoke than in the rim, so that after casting, the former 



44 PATTERN MAKING. 

cools more slowly than the latter, with the result that, if the spokes 
are straight they will pull squarely against the rim and set up 
internal stresses which are apt to crack the metal. With the 
curved spoke, on the other hand, the metal yields like a spring 
and does not break. 

In making the wooden pattern, Fig. 75, for the spokes, the 
first matter to be determined is the largest diameter of shaft upon 




Fig. 75. 

which it is to be run. An ordinary rule is to make the outside 
diameter of the hub twice the diameter of the shaft, and the curve 
of the spokes should sweep down and merge into the hub. Then 
we should consider the number of spokes, which should vary with 
the diameter of the pulley ; but it should be remembered that an 
odd number is better than an even, because then no spoke in 
shrinking, is pulling directly against any other. As for the 
dimensions of the arms, a trained eye is as good a guide as any 



PATTERN MAKING. 45 



rule. But for the beginner the following formula is safe to 
follow : 






d X w 



n X 8 

in which 

b = the breadth of the arm at the outer end, 

d = the outside diameter of the pulley, 

w = the width of the rim, 

n = the number of spokes, 
all dimensions being taken in inches. 

Thus for a pulley 24 inches in diameter with a rim 6 inches 
wide and fitte'd with 5 spokes, the formula becomes : 



b = V24XJ = */ 36 
V ft v 8 V 



5X8 

Hence, b = 1.53 inches or 11 inches. 

The width of the spoke should be one-third greater at the 
hub than at the rim. The thickness at the hub and rim should 
be one-half the width, and the section should be elliptical. The 
spoke just calculated then becomes, 

11 inches wide at rim, 

|- inch thick at rim, 

2 inches wide at hub, 

1 inch thick at hub. 
The curve of the pulley arm should be so designed that there 
is an ample curvature to permit the yielding already referred to, 
and yet be straight enough to have the requisite stiffness. The 
usual method employed in designing these spokes is to roughly 
outline the arm with a pencil to a graceful shape and then adapt 
radii to it so that it may be drawn with instruments. 

The common method of constructing the pattern is to make 
each spoke of a separate piece of wood with the grain running in 
the general direction of the spoke and fasten them together at the 
center with glue and a flat plate or ring as in Fig. 75, which can 
also be used as a rapping plate. This need only be split or made 
in two pieces in the case of very large and heavy wheels. For all 
ordinary work it can be made in one piece and moulded as directed 
in connection with the hand wheel on page 32. 



46 PATTERN MAKING. 

The hubs are usually loose and are held central by a single 
dowel pin. Their diameters are adapted to the size of the shaft 
upon which the pulley is to run, and the length is proportioned to 
the width of the rim as well as its diameter. The length of the 
boss should be about two-thirds the width of the rim except in 
the cases of tight-and-loose pulleys where the hub should be a 
trifle longer than the width of the rim. It may then project about 
X inch on the sides in contact and ^ inch on the outside. 

Rapping Plates. In the description of the making of the 

pulley pattern the ring serving as a binder for the hub is spoken 

of as a rapping plate. When a pattern is imbedded in the sand, 

the latter is closely compressed all about it and slightly adheres. 

The moulder is, therefore, in the habit of rapping the pattern 

gently in order to loosen it in the sand before attempting to draw 

it. If the pattern is not provided with a metal plate, the moulder 

will drive the sharp point of a lifter into the wood 

and strike it alternately on opposite sides and at the 

same time use it to lift the pattern from the sand. 

This mars the pattern and will in time ruin it. The 

rapping plate, Fig. 76, is a piece of thin metal i to 

■=% inch thick, inserted so that it is flush with the 

parting face of the pattern and is held by wood 

Fig. 76. screws with countersunk heads. These plates are 

drilled and tapped for a | inch screw and should 

be the same for all the patterns in the foundry so that one set of 

rods can be used interchangeably. The method of using is to 

screw the rod into the plate and rap it gently to and fro until the 

pattern has been loosened, when it may be lifted. For small 

patterns one rapping plate will be sufficient and this should be so 

placed that the hole for the lifting rod comes directly over the 

center of gravity of the piece. This will prevent tilting of the 

pattern as it is lifted from the sand. For medium sized patterns, 

two rapping plates should be provided, so that the pattern can be 

raised from two opposite sides. For still larger patterns three or 

four rapping plates are used ; the object being to give such perfect 

control when drawing that there can be no tearing away of the 

sand. 

Metal Patterns. In the pattern for the pulley a portion of 




PATTERN MAKING. 47 

it is described as made of iron. Metal patterns are extensively- 
used where either one of two conditions prevail: first, where the 
character of the work is so light and delicate that a wooden pattern 
would not be able to hold together, such as in ornamental castings ; 
and second, where such a large number of castings are to be made 
that the wooden pattern would not last long enough to complete 
the job. This latter condition prevails where brake shoes are 
made by the thousand from a single pattern. 

The metal pattern may be made of iron or brass. The work 
of forming it should be very carefully performed and it should be 
turned, planed, and filed so that it is perfectly smooth. If brass 
is used, it is customary to give it a light coating of shellac varnish, 
but it is not absolutely necessary. Where iron is used some pre- 
servative must be put upon the surfaces to protect them from rust. 
The best method is to warm the metal and rub it with a rag dipped 
in melted beeswax. This excludes the air and leaves a smooth 
surface so that it is easily drawn out of the sand. This, however, 
is not a very durable protection ; the more common method is to 
use a shellac varnish. In order that the varnish may adhere, the 
metal should first be wet with a solution of sal ammoniac and 
allowed to dry ; it is then sandpapered and varnished. 

Varnishing. For two reasons all patterns should be varnished 
before being sent to the foundry. First, the varnish forms a pro- 
tective coating to the wood or metal against the moisture in the 
sand of the mould ; second, it gives a smooth glossy surface to the 
pattern so that it is easily withdrawn from the mould. The varnish 
universally used by pattern makers is shellac. It should always 
be prepared in the shop where it is used. It is made by dissolv- 
ing shellac in alcohol in the proportion of two pounds to the 
gallon. The actual dissolving may, however, be done by putting 
the shellac in the bottom of an earthenware vessel and pouring in 
enough of the liquid to cover it. This will make a varnish too 
thick for use but it can be thinned to the proper consistency by 
the addition of more alcohol. The varnish should always be kept 
in an earthenware vessel as a metallic one is apt to discolor it. 
The varnish pot should be fitted with a close cover with a hole for 
the handle of the brush which should be suspended in the pot. 

It is customary to apply the varnish clear which will thus 



IS 



l'ATTKRN MAKING. 



give ft yellow color, For the oore printsa small quantity of ivory 
lampblaok is added to the varnish before applying. The prints 
being blaok enables the moulder to decide the use for which they 
are intended, 

Sometimes Frenoh vermillion is put in the varnish for the 
body of the pattern, blaols being put upon the ooreprints, Any 
ooloring matter may be used, but to obtain an even oolor the coat 
should be light, Where heavy pigments are mixed with the 
varnish they quickly sink to the bottom and frequent stirring is 

necessary, 




Fig, 77. 





i i 



Figa, 80 and 81, 



Fig. 79, 



Valves. The outside contour of castings may be quite 
smooth and even, while the cores, by which the interior is formed, 
are very irregular. Such is the case with an ordinary globe valve 
easing whose external appearance is shown in Fig, 77. A side 
elevation of one-half of the oorebox, Fig, 78, however shows that 
the interior is of a very irregular form. The external appearance 
of the pattern should be the same as the body of the valve shown 
in Fig. 77. It should be built up of thin pieces glued together, 
except for valves intended for | inch pipe or less, when, the halves 
may be each of a single piece of wood, including the coreprints. 

It is the core-box that will give the greatest amount of trouble 



PATTERN MAKING. 49 

The elevation of the face and horizontal section of the core-box, 
Fig. 79, shows that the interior is irregular in form and that the 
halves of the core must be made in separate boxes and pasted 
together. This box must be cut out entirely by hand tools as the 
irregularity of the interior makes it impossible to use any machine. 
The method of procedure is to lay out upon the face of each 
half of the core-box, the outline corresponding to that of the 
core-prints! At the ends semi-circles should be described to 
outline the edges of the print. For cutting out the interior cores 
a and />, Fig. 78, it is well to make wooden templates so that the 
core may be easily cut to the required depth. If made too deep the 
metal of the seat would be thinner than it should be ; if not deep 
enough, the passages would be contracted and the weight of the 
valve increased. These templates should have a form resembling 
the contour of a vertical section of the passages for which they are 
intended. Thus a template for the narrow neck of a would be 
shaped as in Fig. 80, and for the space beneath the valve seat in 
b as shown in Fig. 81. 

After the core-boxes have been carefully cut out with the 
hand tools, they should be scraped, sandpapered, and shellaced. 

The pattern itself can be turned in the lathe, the two parts 
being held together as by the method described in connection with 
the pipe pattern, Fig. 69. After the turning has been done the 
hexagonal ends should be cut out of the same material. This may 
be done if the rough material at these points is left untouched by 
the turning gouge and chisels. Turning leaves the body in the 
shape of a globe. After the hexagonal ends have been cut, the 
neck for the stuffing-box and the stem is to be turned and glued 
in position. 

As the line of intersection of the cylindrical neck and the 
spherical case is a circle, it is simply necessary to flatten the top of 
the case and lay the neck upon it. The connection between the 
two at a, will then be angular and must be eased off by the use of 
a fillet. The coreprint of the neck is turned solid with the neck 
itself which must, of course, be made in halves like the body of 
the valve. 

Where a piece is laid upon a pattern in this way it is well to 



50 



PATTERN MAKING. 



strengthen the glued joint by the use of a thin plate of metal 
firmly screwed to the two parts thus united. 

Pillow Blocks. In the ordinary pillow block, Fig. 82, we 
revert, once more, to the single-piece pattern. These patterns are 
exceedingly simple to construct. They are in such constant 




Fig. 82. 



O 



o 



o 



o 



Fig. 83. 



demand that every pattern shop is frequently called upon to make 
the different sizes. 

Where the width of the block of the length of the bearing is 
not more than 12 inches, the base, B, may be made of one solid 
piece of board ; one face should be left smooth if it is intended to 
finish the bottom in a machine. If the bottom is to be chipped to 



PATTERN MAKING. 



51 



fit into its position it should be ribbed as shown in Fig. 83. The 
height of the ribs should be about |- inch. 

Upon the upper face should be glued and nailed the body of 
the block. It should be built up and the shaft core should be cut 
out with the core-box plane as already described for the core-box. 
It will facilitate this work if the grain of the wood is laid to run 
across the block. 

As blocks of this kind are usually babbitted upon the rough 
casting, provision must be made to hold the same. For this pur- 
pose a narrow rib is made around the inside of the box at the ends 
as shown by the dotted lines of Fig. 82. The top of this rib 
should be ^ inch wide, the bottom | inch and its height should be 
dependent upon the nominal size of the box. For large boxes of 




Fig. 84. 

eight inches or more diameter they may be f inch high, but for 
ordinary boxes \ inch is enough. The top of the rib should be | 
inch from the shaft. That is to say, the diameter, d, should be 
\ inch greater than that of the shaft for which the box is intended. 

After the box has been formed the coreprints, a a, are to be 
fastened on, and the prints, b b, put on loosely so that they may 
be imbedded in the sand of the cope. The cores which are set in 
these prints form the bolt holes by which the block is held to its 
foundation. 

In moulding, pillow blocks are cast bottom up, thus insuring 
sound metal for the completed casting. 

The cap for this block, Fig. 84, is made in one piece, it being 
quite possible to cut away the sand so that the parting between 
the cope and the drag will come along the line e e as described in 
connection with the handwheel, Fig. 58. 



52 



PATTERN MAKING. 



This pattern is also cast bottom up, insuring sound metal on . 
the top that is exposed to view. 

Bearings. Where babbited boxes are not used, it is custom- 
ary to insert a brass or soft metal bearing for which a special 
pattern is to be made. The details of such a pattern do not differ 
in any way from those intended for use in iron castings, but a 
slightly different shrinkage rule must be used. 

Columns differ somewhat from pipes. Instead of a smooth 
outer surface they are commonly fluted or fitted with ornamenta- 
tions of some sort. It will be seen by reference to a half section 
of a fluted column, Fig. 85, that if the pattern were to be made 
like the completed casting it would be impossible to get it out of 
the mould without tearing away the sand where the pattern is 
under cut as at a! a'. Loose pieces are therefore used. 

The body of the pattern is made 
, octagonal as shown by the line ABODE. 
The loose pieces forming the flutes are held 
to the main body by pins that stand at 
right angles to the line A E. After the 
sand has been rammed, the body included 
in the lines A B C D E is lifted out leav- 
ing the parts A a b B, B b c C, etc., imbedded in the sand. Then 
one after another these are lifted out. 

These fluted sections should never be so faw in number that 
they cannot be lifted out without tearing the sand. In small work 
six sections can be used ; eight is better and in some twelve are 
needed. 

Other forms of ornamentation are put upon columns in a 
similar manner. Leaves or flowers are held by pins or in grooves 
in such a way that the main body of the pattern can be lifted out 
without disturbing them, and they are then withdrawn from the 
sand through the cavity left by the main pattern. 

Cores for Columns. Cores for columns may be made in core- 
boxes as in the case of those for pipe, but where the core is long 
and straight no core-box is needed. The core is usually built of 
loam about an iron pipe as will be explained in the section on 
Foundry Work. 




Fig. 85. 



PATTERN MAKING. 



53 



5 



Where the core is to follow the lines of the ornamental mould- 
ings on the outside of the column, it may be provided with a special 
core-box or better with a sweep as shown in Fig. 86. This sweep 
is used to shape the loam core that is to be built up on an iron 
pipe. 

Fig. 86 is the outline of the template 
that is to be used in sweeping the core for 
the interior of the columns shown in Fig. 87. 
Thin Patterns. Where the casting to 
be made is thin extra precaution must be 
taken. The unequal pressure caused by 
ramming the sand will distort a thin pattern 
so that the casting will not have the proper 
outlines. This may be prevented by support- 
ing the pattern while the sand of the nowel 
is being rammed about it. 

Fig. 88 represents a section of a railing 
cap. If the pattern B were to be set with 
its edges a a resting upon the moulding board 
and the sand of the drag rammed down upon 
its upper face, it would be sprung out of 
shape. To avoid this the follow board A is 
made to exactly fit the under side of the pat- 
tern. Then when the sand is rammed, the f^ 
whole pattern is supported and there will 

be no distortion. When the cope is rammed the follow board is 
removed and the sand of the drag supports the pattern. 

Thin patterns and all that are 
likely to suffer from distortion due 
to sand pressures should be pro- 
vided with accurately fitting follow 
boards, and where the number of 
castings is large, the patterns themselves should be of metal. 
Engine Cylinder. Engine cylinders may be made in either 
of two ways. There may be a regular pattern or a loam mould 
may be constructed. The latter method will be fully described in 
the section on Foundry Work. It may be stated in general that 
loam moulding is used for cylinders of large dimensions and pat- 



I 




86. 



Fig. 87. 




Fig. 88. 



54 



PATTERN MAKING. 



terns for those of small. The dividing line varies in different 
foundries and ranges from 24 inches to 30 inches of diameter. 

In order that a pattern maker may construct a cylinder 
pattern, he should be provided with drawings showing in detail a 




Fig. 89. 

longitudinal section, a cross-section, and a plan of the completed 
cylinder as in Figs. 89, 90, and 91. The longitudinal section 

should be redrawn to full size 
on a chalked board as described 
on page 3. 

In order that the weight of 
the pattern may be as small as 
possible the cylindrical portion 
should be built up and hollow. 
The dotted lines (Fig. 89) at 
A, B, and at the ends indicate 
the core-prints on the pattern. 
First as to the two latter, it will 
be seen that they are smaller in 
diameter than the finished bore. 
This is to allow for finishing as 
already explained. 

The barrel of the cylinder is to be constructed first. This 
should be made up of strips one inch thick. First cut four pieces 
as A A (Fig. 92) carefully jointed in pairs along the line a a. 




Fie. 90. 



PATTERN MAKING. 



55 



These are to form the ends of the barrel. They should be fastened 
by dowels. The number of faces of the polygon should depend 
upon the size of the cylinder. 

Next cut and fit on each face of the polygon the strips b b, 
glueing and nailing them in position. Thus a hollow polygonal 











; ! 












































s 

* 




















-I 







Fig. ©1. 

prism will be formed, which may be centered on its parting line 
a a and turned to a cylindrical form. 

When this has been done the casing 

for the passage of the ports and the plugs 

for supporting the cylinder are built upon 

the curved faces of the cylinder as turned 

! a and the steam-chest seat laid on. 

The core prints for the ports and 
exhaust pipe are then glued on and finally 
the core-prints for the body fastened. 
These latter may, however, be built on the 
polygonal ends at the same time as the 
body. Or, they may be made in the same way and screwed 
to the ends after the completion of the pattern. The latter method 
usually makes the lightest job. 

The core-boxes of a cylinder pattern are usually somewhat 
intricate. The core for the main body is simply cylindrical like 
that used for pipes except that in two places a piece is set upon 
the inner surface of the box. These form indentations or prints 
in the core itself to receive the cores forming the ports. If desir- 
able the core may be made of loam. 




Fig. 92. 



56 



PATTERN MAKING. 



The cores of the ports must have a curvature on their cross- 
section at the points d d, Figs. 93 and 95, to conform to the curve 
of the cylinder's shell. In order that the shape of the port shall 
correspond with that called for by the drawing, first make a template 
to exactly correspond with the full-size drawing of the port as given 
in Fig. 89 and duplicated on the chalk board. 












a 






b r 




i r 






^y /; 


ro 




iiL 




8 



Fig. 93. 




*b^ 

"TTl — * 
! C 

-a 



Fig 94. 



Fie. 9i 



Build up a block of which Figs. 93, 94, and 95 are general 
outlines. In these three figures the same letters refer to the same 
parts. Square the edge a a and from it lay off the width and 
length of the port according to the dimensions b and C respectively. 
On the face d describe the arc of a circle g h from the point e, 
letting the perpendicular distance / from a to e be equal to the 
distance from the valve face to the center of the cylinder plus the 
height of the core-print on Fig. 89. 

Then with the template of the port for a guide, cut out the 
material of the block so that it fits accurately along the center line 



PATTERN MAKING. 57 



from the edge a to the curve g h. Take the distance a b on Fig. 
89 for a radius and strike an arc whose cord is equal to the length 
of the port (Fig. 94). With the concave surface of this arc as 
a template cut away the material of the block to form the bottom 
of the core as shown by the line i k of Fig. 94. The edges, almd 
of Fig. 93, bounding the core ends i h should rise the width of the 
port, away from the bounding line at the bottom as shown by the 
dotted line p r s. The cover to this core should fit the. faces A 
and B of Fig. 94 and have the same curvature over the body of 
the core as i k. The sides of the core where they intersect the 
valve-seat at a and along the shell of the cylinder at d s are flat. 
These two parts exceed the length of the cored passages by the 
length of the prints. One core-box will answer for both steam 
ports. 

The core-box for the exhaust passage is a simpler box to 
make. It is made in halves the face view of each being the same 
as that of the exhaust passage A, as shown in Fig. 90 and its 
depth beneath the port is equal to and shaped like the correspond- 
ing portion A of Fig. 89. Beyond the valve-face the part B is a 
half-circle in each box. The length of the box exceeds that of 
the cored portion by the dotted lines indicating the core prints on 
Fig. 90. 

Gears. Spur gear patterns may be made in either one of two 
ways : by a complete pattern or by a segment. Complete patterns 
are usually made where the gears are not more than 30 inches in 
diameter and a large number of castings are needed. The propor- 
tioning and shaping of the tooth will be treated elsewhere in this 
course. 

The hub and spokes of gear wheels depend for their size and 
proportions upon the work which the wheel is to perform. Wheels 
whose pitch diameter is from 10 to 24 inches should have four 
arms and for smaller diameters should have a continuous plate or 
web. A safe rule for the width of the arms at the rim is to 
make it twice the pitch. The following formula is, however, 
preferable : 

B 2 . _ 7-34 X P X W X y/N" 
A 



58 



PATTERN MAKING. 




In which 

P = the pitch, 
W = length of the tooth, 
N = number of pinions to be driven, 
A = number of arms, 
B = breadth of arms. 
The arms should be tapered from the rim to the hub ; the 
amount being about -| inch to the foot. 

The rim should 
be built oip of thin 
strips carefully fitted 
and always breaking 
joints. 

The teeth may 
be glued and nailed 
or dovetailed to the 
periphery. The for- 
mer is the cheaper 
method ; the latter the more durable. 
In either case the blocks from which the 
teeth are to be cut are put on in the 
rough as shown in Figs. 96 and 97. 
After the glue has thoroughly set, the 
teeth are laid out and then shaped 
with a chisel. Where the length of the tooth does not exceed 4 
or 5 inches it is best not to allow any draft, or if any is allowed to 
make it as little as possible, for it is very desirable that the line 
of the tooth should be at right angles to the plane of the pitch 
circle. Where there is a draft, that of the gear and the pinion 
should run in opposite directions so that the teeth may have a 
proper bearing throughout their whole length when placed on par- 
allel shafts. These gears are usually in one piece and are moulded 
like the handwheel, Fig. 58. 

For large gearing it is customary to make only a short seg- 
ment containing from three to five teeth, which is swung from a 
center and successively used in different positions to mould the 
whole gear as will be explained in the section on Foundry 
Practice. 




PATTERN MAKING. 



59 



Bevel Gearing. To make a bevel gear pattern is much more 
difficult than that of a spur gear. The hub, spokes, and rim are 
laid up and made in the same way. In cutting the teeth it must 
be remembered that all lines marking the contour of the teeth con- 
verge to a common point, which is the point of intersection of its 
own shaft and that of its mate. 

Fig. 98 illustrates the method to be pursued in the laying out 
and shaping of the teeth. The drawing gives the taper of the 

crown and root of the 
teeth along the bound- 
ing lines towards the 
vanishing point C. 

On the face a at 
right angles to the 
pitch line a C lay out 
the face of the larger 
end of the teeth, and 
on the corresponding 
end g lay out the 
smaller ends. Then 
work them down to 
size with an even 
taper from a to g exactly as in the case of the spur gearing. 
Worm Gearing. To strike out a worm and its gear. First 
draw a right angled triangle in which a c (Fig. 99) is the cir- 
cumference of the worm ; a b the pitch and the angle a c b will 
represent the inclination of the teeth. 

The worm pattern should be made first and in two pieces. 
Lay out the shape of the teeth as in a rack as described in the 
course of Mechanical Drawing, Lesson 20, Cut a triangle like Fig. 
99 out of paper and wrap it about the turned block of the worm. 
The edge b e will indicate the center line of the tooth. Con- 
tinue this until the whole length of the worm has been laid out 
with a continuous helix. Then with a template shaped to fit the 
spaces between the teeth either work it out by hand, or better 
still, turn it out on a screw cutting lathe. 

The wheel may be built up like those of other gears but must 
be made in halves held together by dowels. 




Fig. 98. 



60 



PATTERN MAKING. 



The most expeditious way to cut the teeth will be to lay them 
out as they would come from the repetition of the work for a gear 
in connection with a rack (see Lesson 20, Mechanical Drawing). 
This shape is laid out on the center face of each half of the pat- 
tern, and, after roughing them out but not working down to the 
line, the worm is placed in a lathe and the gear on a shaft. 
Then the teeth are red-leaded and worked down e 

until a complete surface contact is obtained. 
This is a rule-of-thumb but will be found more 
expeditious than an attempt to make a scientific 
laying out of the work. 

Cogging. Gearing with wooden teeth is 
in common use where it is desired in case of 
accident that the teeth may break rather than 
anything more important and where the noise of 
common gearing is to be avoided. 

While the placing of new cogs in a gear is 
not, strictly speaking, pattern work it is usually 
assigned to the pattern maker. The body of the 
cogged wheel is of cast iron and the rim is 
cored out with rectangular holes corresponding 
in number and approximately in size to the teeth 
in the completed wheel. It is into these holes 
that the teeth are inserted. 

In the selection of the wood for these teeth, 
only strong, dry, straight-grained hard wood 
should be used. Maple is probably the best 
for the purpose. It should, above all things, be 
dry for if it is damp or contains any sap, it will 
shrink after it has been put in position and become loose in the 
casting. 

The teeth when first inserted are cut with a shank that has 
a driving fit in the cores of the rim. This shank projects down 
through the rim for a distance of 1| or 1± inches where one side 
should be cut away to form a half dovetail and a wedge may be 
driven tightly between it and the adjoining tooth. This wedge 
should bear against the shank of the teeth on each side and the 
inside of the rim. These wedges should not be inserted and 



Fier. 99. 



PATTERN MAKING. 61 

driven home, one at a time, but should all be put in position and 
then struck in rotation until all are tight. The wheel should then 
be allowed to stand in a warm, dry place for a week and the 
wedges again tightened. 

The shape of the teeth is laid out on each end of each tooth 
and the wood worked down to the proper form as directed for the 
making of spur gearing. 

Finishing Patterns. A pattern should be made hard and 
smooth so that it can be easily drawn from the sand. It should 
be protected by a coating that will not be affected by the moisture 
contained in the sand. Shellac varnish is a good material for such 
a coating. 

In the finishing of a pattern it should first be sandpapered 
smooth. It is then given one coat of shellac varnish. This will 
roughen the wood and after the varnish is dry a second sandpaper- 
ing will be required. Then a second and sometimes a third coat 
of varnish is laid on, when the pattern will be ready for the 
foundry. Never put on a coat of shellac until the previous one is 
perfectly dry and hard. Let the varnish dry slowly in the air and 
do not hasten it by putting the pattern near a stove or heater. 
An hour is usually quite sufficient to harden a coat of shellac 
varnish. 

Parts where slivers or small pieces have been chipped off may 
be mended with beeswax. It is best applied with the warm blade 
of a knife. Hold the blade in an alcohol flame or that of a 
Bunsen burner for a moment and then cut off a bit of wax which 
will melt on the blade and may be rubbed into the broken part of 
the pattern; the process being repeated until the break is filled. 

Paint and ordinary varnish should not be used on patterns. 

Files are frequently of service in finishing patterns ; the half- 
round being a particularly convenient tool. 



PATTERN MAKING 



EXAMINATION PAPER 



American 
School of Correspondence 



Copyrighted 1898 



BY 



American School of Correspondence 



BOSTON, MASS., 
U. S. A. 



PATTERN MAKING. 



Instructions to the Student. Place your name and full address at the 
head of the paper. Work out in full the examples and problems, showing each 
step in the work. Mark your answers plainly "Aus." Avoid crowding your 
work as it leads to errors and shows bad taste. Any cheap, light paper like 
the sample previously sent you may be used. After completing the work add 
and sign the following statement. 

I hereby certify that the above work is entirely my own. 

(Signed) 



1. What woods are most suitable for small patterns? 

2. What tools should be used for finishing lathe work? 

3. What is the usual allowance for finishing? 

4. Why can work be done more rapidly upon a band than 
upon a jig-saw ? 

5. How can a solid pattern be moulded so that it is 
imbedded in both cope and drag ? 

6. Why is it usually necessary to make a pattern in two 
parts ? 

7. What precaution should be taken in the preparation of 
the wood in making a glue joint ? 

8. What should be the outside diameter of the original 
wooden pattern for a pulley rim, the finished pulley to be 3 feet 
in diameter : (a) when measured by a common rule ; (ft) when 
measured by a shrinkage rule ? 

9. How are iron patterns usually protected from rust ? 

10. Should a gear wheel 16 inches in diameter have spokes 
or a web to connect the rim and hub ? 

11. What are the principal requisites of a material for 
patterns ? 

12. What are the qualifications of a pattern-maker ? 

13. What are the two parts of a flask called ? 

14. What is a faceplate? 



66 PATTERN MAKING. 

15. How are the two parts of a round pattern held together 
for turning ? 

16. How can the setting of glue be quickened? 

17. What should be the breadth of the outer ends of the 
spokes of a pulley whose diameter is 2 feet, 6 inches and the width 
of the rim 8 inches, there being five spokes? 

Ans. 1.81 inches. Use 1-| inches. 

18. In the making of a pattern for an engine cylinder, what 
is made first? 

19. What woods are in most common use for patterns? 

20. What is the advantage of a sliding carriage on a turn- 
ing lathe ? 

21. What is the usual allowance for finishing? 

22. Why are large patterns not made of a single piece of 
wood ? 

23. How is overheating avoided in the preparation of glue ? 

24. What should be the breadth of the outer ends of the 
spokes of a pulley, whose diameter is 3 feet, the width of the rim 
10 inches, there being five spokes? 

Ans. 2.08 inches or 2 inches. 

25. How are engine cylinders made? 

26. How should wood be inspected? 

27. What will be the linear velocity of the rim of a circular 
saw 16 inches in diameter when running at a speed of 2,500 revolu- 
tions per minute. Ans. 10,472 feet per minute. 

28. How should a saw table be equipped ? 

29. What are dowel pins and what are they for? 

30. What is the effect of prematurely chilling the glue 
after it has been applied to the surface which it is desired to 
unite ? 

31. How are the coreprints of a pattern designated 9 

32. To what extent should a pattern maker be a draughts- 
man? 

33. At what speed should the pulleys of a band saw revolve 
if they are 3 feet in diameter ? 

Ans. About 370 revolutions per minute. 



PATTERN MAKING. 67 

34. What is the purpose of the allowance for finishing on 
patterns ? 

35. What effect does overheating have upon glue? 

36. What is the purpose of a rapping-plate ? 

37. Why does wood warp? 

38. What is a convenient allowance for draft? 

39. What is a two-part pattern ? 

40. How many spokes 21 inches wide at the rim should be 
put into a pulley 4 feet in diameter and having a rim 9 inches 
wide? Ans. 5.6. Use 6. 

41. How should wood be seasoned ? 

42. What power-driven tools should be in a pattern shop ? 

43. How long a time does glue require to set? 

44. How can a pattern that has been slightly damaged be 
repaired ? 

45 . What is the draft of a pattern ? 

46. Why are two shrinkages allowed for in the making of a 
wooden pattern for an iron one ? 

' 47. Why is white pine a suitable material for pattern- 
making? 

48. When should cores be used instead of allowing the pat- 
tern to make its own cores ? 

49. How long a time is required to harden a coat of shellac 
varnish? 

50. How is a round core made ? 

51. Which will dry the more rapidly, large or small timber 
and why ? 

52. How can the tendency of glued strips to curl be 
diminished ? 

53. What is the use to which cores are put? 

54. What should be the breadth of' the arm of a gear wheel 
whose pitch is 1^ inches, the length of whose tooth is 4 inches, 
which drives one pinion and has five arms ? 

Ans. About 2.7 inches. 

55. How is shellac varnish prepared? 

56. What proportion of glue and water should be used in 
the preparation of glue ? 

57. Are coreboxes needed for columns? 



68 PATTERN MAKING. 



58. What is the proper way to hold a tool on the grind- 
stone, when sharpening? 

59. Are complete patterns needed for the moulding of gears ? 

60. What is the use of cores ? 

6.1. What is meant by "allowance for finishing" on a 
pattern ? 



LIBRARY OF CONGRESS 



003 318 170 ft • 



